Structural characteristics of the bone surrounding dental implants placed into the tail-suspended mice.

BACKGROUND: There are many unclear points regarding local structural characteristics of the bone surrounding the implant reflecting the mechanical environment. PURPOSE: The purpose of this study is to quantitatively evaluate bone quality surrounding implants placed into the femurs of mice in an unloading model, and to determine the influence of the mechanical environment on bone quality. METHODS: Twenty 12-week-old male C57BL6/NcL mice (n = 5/group) were used as experimental animals. The mice were divided into two groups: the experimental group (n = 10) which were reared by tail suspension, and the control group (n = 10) which were reared normally. An implant was placed into the femur of a tail-suspended mouse, and after the healing period, they were sacrificed and the femur was removed. After micro-CT imaging, Villanueva osteochrome bone stain was performed. It was embedded in unsaturated polyester resin. The polymerized block was sliced passing through the center of the implant body. Next, 100-µm-thick polished specimens were prepared with water-resistant abrasive paper. In addition to histological observation, morphometric evaluation of cancellous bone was performed, and the anisotropy of collagen fibers and biological apatite (BAp) crystals was analyzed. RESULTS: As a result, the femoral cortical bone thickness and new peri-implant bone mass showed low values in the tail suspension group. The uniaxial preferential orientation of BAp c-axis in the femoral long axis direction in the non-implant groups, but biaxial preferential orientation of BAp c-axis along the long axis of implant and femoral long axis direction were confirmed in new bone reconstructed by implant placement. Collagen fiber running anisotropy and orientation of BAp c-axis in the bone surrounding the implant were not significantly different due to tail suspension. CONCLUSIONS: From the above results, it was clarified that bone formation occurs surrounding the implant even under extremely low load conditions, and bone microstructure and bone quality adapted to the new mechanical environment are acquired.

Study on bone quality in the human mandible-Alignment of biological apatite crystallites.

The importance of considering bone quality during oral implant treatment is increasingly being recognized. Assessment of bone quality in response to changes in the jaw bone is extremely important when planning treatment. The present study analyzed biological apatite (BAp) crystallites, a bone quality factor, in order to investigate crystallographic anisotropy in dentate and edentulous human mandibles. Using mandibular samples from Japanese adult cadavers, a region of interest was established comprising cortical bone in the central incisors. Samples were classified into five morphological categories based on the extent of bone resorption. Bone mineral density (BMD) was measured and diffraction intensity ratios were calculated using a microbeam X-ray diffraction system. While no differences were observed in BMD, differences were observed in BAp crystallite alignment between the measurement points. In the alveolar region, samples with residual alveolar bone showed strong alignment in the occlusal direction, while samples with marked alveolar bone resorption had preferential alignment in the mesiodistal direction. The present findings suggest that tooth loss and the extent of alveolar bone resorption affects bone quality in the mandible. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B: 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 838-846, 2019.

An aged bull with concurrent thyroid C cell carcinoma, adrenal pheochromocytoma and pituitary chromophobe adenoma.

A Japanese Black bull aged 20 years died following progressive loss of the body weight. Pathological examination disclosed multiple endocrine tumors including thyroid C cell carcinoma with metastases to the cervical lymph nodes and lung, adrenal pheochromocytoma and pituitary chromophobe adenoma in the pars distalis. The serum calcium content was as mildly low as 8.0 mg/dl at the terminal stage. The bull had daily ingested the ration containing 1.9 times the recommended calcium amount for 8 years and 120,000 units of vitamin D(3) for 5 years prior to death. The long-term dietary intake of moderately excessive calcium with vitamin D(3) might be related to the pathogenesis of the thyroid C cell carcinoma.

Effect of fatty acids added to the milk replacer on white scour and excretion of fatty acids in Holstein calves.

In order to examine the relationship between white scour and fatty acids, we added fatty acids to the milk replacer. Twenty healthy Holstein calves were divided into 4 groups, five calves per group; a control group with no fortified fatty acid, and 3 groups fed either with oleic, stearic, or palmitic acid, respectively. The calves were fed milk replacer (5% of the calf's body weight) twice a day but the fatty acids (2 wt % of milk replacer) were added only once. The fecal and blood samples were obtained at 0, 12, 24, 36, and 48 h after feeding of the acids. All five calves in the palmitic acid group, and 3 out of 5 calves each in the stealic and the oleic acid groups had whitish feces after feeding fatty acid. The stearic acid group had a significantly elevated stearic acid concentration in the feces during 24-36 h compared to the pre-feeding level. The fecal concentration of palmitic acid increased significantly at 24-36 h in the palmitic acid group. We concluded that the long-chain saturated fatty acids are one of the causes of white scour in calves.